Synthesis and optical properties of CdS quantum dots embedded in silica matrix thin films and their applications as luminescent solar concentrators

Reda, S.M.

doi:10.1016/j.actamat.2007.09.017

Cited by 111 publications

(56 citation statements)

References 2 publications

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“…Several research groups claimed that the incorporation of QDs into a solid matrix can lead to a blue-shift in both their absorption and emission, caused by surface oxidation of the QD during the manufacturing process. [89,136,139] In addition to a blue-shift in emission wavelength, the emission intensity in QD solar concentrators also is dependent on the nature of the host matrix. For example, CdSe/ZnS QDs in a solid matrix lose 22.5-96% of the emission intensity they exhibited in solution.…”

Section: Quantum Dotsmentioning

confidence: 99%

Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Debije

Verbunt

2011

Advanced Energy Materials

829

689

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Research on the luminescent solar concentrator (LSC) over the past thirty‐odd years is reviewed. The LSC is a simple device at its heart, employing a polymeric or glass waveguide and luminescent molecules to generate electricity from sunlight when attached to a photovoltaic cell. The LSC has the potential to find extended use in an area traditionally difficult for effective use of regular photovoltaic panels: the built environment. The LSC is a device very flexible in its design, with a variety of possible shapes and colors. The primary challenge faced by the devices is increasing their photon‐to‐electron conversion efficiencies. A number of laboratories are working to improve the efficiency and lifetime of the LSC device, with the ultimate goal of commercializing the devices within a few years. The topics covered here relate to the efforts for reducing losses in these devices. These include studies of novel luminophores, including organic fluorescent dyes, inorganic phosphors, and quantum dots. Ways to limit the surface and internal losses are also discussed, including using organic and inorganic‐based selective mirrors which allow sunlight in but reflect luminophore‐emitted light, plasmonic structures to enhance emissions, novel photovoltaics, alignment of the luminophores to manipulate the path of the emitted light, and patterning of the dye layer to improve emission efficiency. Finally, some possible ‘glimpses of the future’ are offered, with additional research paths that could result in a device that makes solar energy a ubiquitous part of the urban setting, finding use as sound barriers, bus‐stop roofs, awnings, windows, paving, or siding tiles.

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Section: Quantum Dotsmentioning

confidence: 99%

Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Debije

Verbunt

2011

Advanced Energy Materials

829

689

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“…[13][14][15][16][17][18] HCl is generally used as a catalyst to promote gelation in the sol-gel technique. However, gelation under basic conditions is preferable for QDs because they are degraded by strong acid.…”

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confidence: 99%

Preparation of Photostable Fluorescent InP/ZnS Quantum Dots Embedded in TMAS-Derived Silica

Watanabe

Wada

Iso

et al. 2017

ECS J. Solid State Sci. Technol.

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Cd-free fluorescent InP/ZnS quantum dots (QDs) have attracted attention for use as color converters of liquid crystal displays. To protect InP/ZnS QDs from oxygen, which degrades them by photo-oxidation during excitation, we fabricated a transparent monolithic silica composite containing the QDs using an aqueous solution of tetramethylammonium silicate (TMAS) as a silica source. The TMAS solution was basic and readily dispersed the negatively charged QDs obtained by ligand exchange of 1-dodecanethiol for 3-mercaptopropionic acid (MPA). A highly transparent monolithic TMAS-derived silica composite containing the MPA-modified QDs (InP/ZnS-MPA@TMAS) was obtained from the aqueous QD dispersion through a sol-gel process. The photoluminescence (PL) quantum yield of InP/ZnS-MPA@TMAS was 21.7%. Changes in PL intensity under continuous 400-nm excitation were measured to evaluate the photostability of the QDs in InP/ZnS-MPA@TMAS. The PL intensity of InP/ZnS-MPA@TMAS was over 90% of the initial value after 180 min, while that of a reference polymethylmethacrylate film containing hydrophobic QDs decreased to 69%. The higher photostability of InP/ZnS-MPA@TMAS than that of the reference film was explained by the TMAS-derived silica acting as a gas barrier to protect the embedded QDs from photo-oxidation by oxygen in air. A quantum dot (QD) is a semiconductor nanocrystal. As the size of a QD decreases, its bandgap widens because of the quantum size effect. The fluorescent wavelength of a QD therefore depends on its size.1 The tunable fluorescent wavelength of QDs means they are applicable to white light-emitting diodes (LEDs) 2 and bioimaging. 3 CdS and CdSe QDs have been frequently studied because their fluorescent wavelength is tunable in the visible range. 4 InP QDs have recently attracted attention because they are Cd-free with low toxicity. InP QDs have been synthesized via hot injection 5 and thermal 6 methods. Yang et al. 6 coated an InP core prepared by the latter method with a ZnS shell to passivate dangling bonds on the QD surface. The obtained InP/ZnS core/shell QDs displayed a high quantum yield (QY) of up to 60%, tunable fluorescent wavelength, and narrow emission peak. The color reproduction range of liquid crystal displays could be improved by using such InP/ZnS QDs as a color converter in the LED backlight.For practical optoelectronic applications, QDs have to retain their photoluminescence (PL) intensity during continuous excitation. However, the PL intensity of QDs decreases over time because of the photooxidation of the QD surface by oxygen.7 One method used to improve the photostability of QDs is formation of a core/shell structure. However, the PL intensity of InP/ZnS core/shell QDs deteriorated to 40% of the initial PL intensity after continuous excitation by 365-nm light for 10 h. 6 Thus, it is difficult to completely avoid PL deterioration even for QDs with a core/shell structure. 6 Incorporation of well-dispersed QDs into a matrix to protect them from oxygen is another way to avoid PL deterioration of ...

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“…Also, there is a clear blue shift in the values of optical band gap after UV irradiation (without filter) for 960 minutes to dye/silver/Triton X-100. The change in with UV irradiation may be attributed to quantum confinement [29].…”

Section: Optical Energy Gap Figures 5(a)-5(f) Show the Plots Of ( ℎ])mentioning

confidence: 98%

Enhancement of Fluorescence and Photostability Based on Interaction of Fluorescent Dyes with Silver Nanoparticles for Luminescent Solar Concentrators

El-Molla

Mansour

Hammad

2017

Journal of Nanomaterials

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For luminescent solar concentrators (LSCs), it is important to enhance the fluorescence quantum yield (FQY) and photostability. Our measurements have demonstrated that the addition of silver nanoparticles to dye solution causes broadening of absorption bands, so the spectral range of sunlight absorbed by LSC has increased. Silver nanoparticles (NPs) were characterized by X-ray diffraction (XRD) and UV-Vis absorption spectra. UV-Vis spectrum showed a single peak at 442 nm due to the surface plasmon resonance (SPR). The position of SPR peak exhibited a red shift after the sample was exposed to UV irradiation (unfiltered light). The optical band gap values have a reduction from 2.46 to 2.37 eV after irradiation for 960 minutes. Such reduction in optical band gap may be due to change in particle size calculated using Mie theory. The photostability of organic dyes used was improved after adding silver nanoparticles. The area under fluorescence spectra of dyes with silver NPs increased by 41-31% when compared with identical dye concentrations without silver nanoparticles as a result of interaction of the species with silver NPs.

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Synthesis and optical properties of CdS quantum dots embedded in silica matrix thin films and their applications as luminescent solar concentrators

Cited by 111 publications

References 2 publications

Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Preparation of Photostable Fluorescent InP/ZnS Quantum Dots Embedded in TMAS-Derived Silica

Enhancement of Fluorescence and Photostability Based on Interaction of Fluorescent Dyes with Silver Nanoparticles for Luminescent Solar Concentrators

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